JP2588037B2 - How to form patina - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for stably forming green and blue with excellent adhesion to a substrate with good productivity.

<Conventional technology and its problems> Conventionally, the surface of copper used for roofs of shrines and temples has been exposed to oxygen, water vapor, carbon dioxide,
Sulfide to the elegant and beautiful green patina {CuCO ₃ · Cu by the action of such chlorides _{(OH) 2, CuSO 4 ·} 3Cu (OH) 2, CuCl 2 ·
It is well known that it is covered with a basic copper salt such as 3Cu (OH) _2, but this patina layer not only brings out a profound and unique aesthetic appearance, but also acts as an anticorrosion film, and therefore, patina. Copper roofs and the like that are covered with will exhibit durability for hundreds of years.

Therefore, in recent years, "green-blue film-forming products" aiming at artificially producing near-natural patina in a short period of time to prevent corrosion of the base material and to achieve decorative or artistic effects have been developed not only for roofing materials but also for building interior wall materials and the like. It has also been found in decorative articles and the like, and many proposals have been made on means for artificially forming a greenish-blue coating close to nature.

These conventional artificial patina forming means are roughly classified as follows.

(A) Chemical conversion treatment by contacting with a chemical solution (for example,
(B) Method of electrolytic treatment in chemical solution (for example, Japanese Patent Publication No.
(C) a method of subjecting a substrate to a chemical conversion treatment, and further applying a coating thereon (eg, a method proposed as JP-A-55-8491), (D) green A method of applying a paint containing a blue-forming substance (for example, a method proposed in Japanese Patent Application Laid-Open No. 55-139467), (E) an adhesive of copper or copper alloy powder on the surface of a copper plate roughened by sandblasting And then applying an artificial patina such as ammonium chloride or ammonium sulfate (for example, a method proposed as Japanese Patent Publication No. 57-52425).

However, the artificial patina-forming means described above is practically a) the rate of patina generation is slow, b) the patina coating is easily peeled off, and the production equipment is costly. C) The green patina is formed stably. And d) poor adhesion due to unevenness, d) poor adhesion of green-blue, e) many man-hours for forming green-blue coating, and poor productivity. In addition, in addition, in general, the base material is generally limited to copper or copper alloy, and if the generated patina surface is not protected by painting or the like, it cannot maintain sufficient adhesion to the base material. There was also a problem. In addition, the protection of green and blue with a paint film cannot be a fundamental solution to the above problem because the ultraviolet ray causes deterioration of the coating composition.

In view of the above, the object of the present invention is to establish "a means for stably forming a green-blue coating film having excellent adhesion and a uniform color tone in a short time regardless of the type of substrate". Met.

<Means for Solving the Problems> The inventors of the present invention have conducted intensive studies from various viewpoints in order to achieve the above object, and as a result, have found that the surface of the base material for forming patina may be roughened if necessary. When a thin film made of copper or a copper alloy is formed on the surface of the substrate after the surface treatment, and then the thin film is treated with “a specific new chemical conversion treatment solution to which an oxidizing agent is added”, the aforementioned “copper or copper” The chemical conversion reaction (corrosion product formation reaction) and the oxidation reaction of the corrosion product proceed simultaneously between the “thin film made of alloy” and the “chemical conversion treatment solution containing an oxidizing agent”. A green-blue coating with a strong and uniform color tone, which closely adheres and is very similar to natural patina, is formed in a short time. "

The present invention has been made on the basis of the above findings and the like. "After forming a thin film made of copper or a copper alloy on the surface of a base material on which patina is to be formed, (a) alkali metal chloride One or two selected from (b) aluminum chloride, (c) stannic chloride, (d) zinc chloride, and (e) lead chloride By treating a solution containing at least one species with a treatment solution containing an oxidizing agent, it is possible to stably form a greenish blue with good adhesion and good appearance in a short time.

Here, the term “substrate for forming patina” refers to not only metal materials such as copper and copper alloys but also ceramics,
Any material such as tile, wood, synthetic resin, etc. can be used, and the material is not particularly limited.

Hereinafter, the present invention will be described in more detail and specifically together with its operation and effects.

In the patina forming method according to the present invention, first, a “thin film made of copper or a copper alloy” is formed on the surface of a substrate. The thickness of the thin film is not particularly limited, but usually 1 to 100
It is good to be about μm, preferably about 5 to 40 μm.
Of course, green and blue can be formed even if the film thickness is less than 1 μm, but this case is not preferable because cracks and the like are easily generated in the thin film. On the other hand, if the film thickness exceeds 100 μm, it becomes difficult to obtain a satisfactory color tone, and it is not preferable in terms of production cost.

As a means for forming the “thin film made of copper or a copper alloy”, a known method such as a plating method, a vacuum deposition method, a sputtering method, an ion plating method, and a thermal spraying method can be applied. Therefore, it is necessary to select an appropriate thin film forming means according to the type of the base material, etc., but it is a dry process, which can be processed quickly, can use a wide range of materials, and has a large adverse effect on the materials. It can be said that the "spraying method", which does not give a thermal spray, is the most preferable means.

By the way, there are various methods such as “flame spraying”, “arc spraying” and “plasma spraying”, and it is known that powder or wire made of copper or copper alloy can be used as a spraying material. However, in the present invention, there is no particular limitation on the thermal spraying method and the thermal spraying raw material. But,
Even if the same material and the same equipment are used, different coatings are formed if the spraying method (that is, spraying conditions) is different,
Attention is needed in this regard. For example, atmospheric conditions (oxygen-acetylene mixing ratio, etc.), spraying distance, wire supply speed, etc., sensitively affect the hardness of the sprayed coating. In addition, the relative speed between the spray gun and the workpiece, the thickness of the coating per pass, the temperature of the workpiece during thermal spraying (In order to increase the adhesion strength of the coating, it is preferable to preheat the base material to an appropriate temperature. ), Many factors that affect the properties of the thermal spray coating, such as the pressure and flow rate of gas and air.

Furthermore, it is generally said that even if the thermal sprayed coating has the same thickness, "the one with many thin layers stacked" has stronger strength than "the one with few thick layers stacked". It needs to be considered. Also, increasing the sprayed thickness per pass causes overheating, so in the case of inner diameter spraying, the relative speed between the spray gun and the workpiece is increased to avoid overheating, and the film thickness per pass is increased. Special care must also be taken to reduce the thickness.

As described above, when a “thin film made of copper or a copper alloy” is formed by thermal spraying, the thermal spraying conditions and the like are appropriately selected according to the type of the base material, the thickness of the thermal spray coating, the desired surface roughness, and the like. There is a need.

On the other hand, when a "copper or copper alloy thin film" is formed by plating or the like, the object can be achieved relatively stably by simply applying, for example, a known electrolytic solution composition, electrolytic conditions, and the like. .

The surface roughness of the “thin film made of copper or copper alloy” thus formed is not particularly limited, but if the surface roughness of the thin film is less than 3 μm, the degree of green and blue coloring is low,
On the other hand, if it exceeds 50 μm, the adhesive strength between the base material and the thin film tends to decrease, so that it is usually 3 to 50 μm, preferably 5 to 40 μm.

By the way, prior to the formation of the “thin film made of copper or copper alloy” on the substrate surface, roughening the substrate surface is
This is extremely preferable in improving the adhesion between the substrate and the “thin film made of copper or a copper alloy”, and further improving the adhesion of the formed patina. Therefore, before the thin film forming process made of copper or a copper alloy, the surface of the base material is subjected to a surface roughening treatment as necessary, so that the surface of the base material is uniformly roughened and the surface is temporarily activated. It is planned.

Generally, there are two methods of roughening the surface of a base material: a chemical method (including an electrochemical method) and a physical method (a mechanical method).
The types are known. Examples of the former include a method of dipping in an acid or an alkali (that is, an etching method) and an electrolytic method, and examples of the latter include a blast method.
“Water jet method”, “Power tool method”, “Hand tool method”
And the like. Therefore, when the substrate is roughened prior to the formation of the “thin film made of copper or a copper alloy” according to the present invention, the surface roughening method depends on the type of the substrate and the desired surface roughness of the greenish blue product. Must be appropriately selected. For example, when the substrate is a metal material, the surface of the substrate can be roughened with high efficiency, and at the same time, rust and other corrosion products generated on the surface of the substrate can be removed. It can be said that the "blast method" is preferable. Moreover, in the blast method, abrasives having various hardness and particle size such as silica sand, steel grid, steel shot, fused alumina (artificial corundum), alundum, carborundum, glass beads, synthetic resin particles, etc. are used. Therefore, in addition to being able to appropriately select a suitable material according to the type of the base material and the like, there is an advantage that the surface roughness can be adjusted by blasting conditions.

The blast method is classified into various types from various viewpoints. For example, from the viewpoint of the method of spraying the abrasive, the blast method can be classified into “a method of blasting by compressed air” and “a method of blasting by centrifugal force”. Also, the abrasives to be sprayed can be classified into "dry method" and "wet method" based on the dry / wet state of the abrasive to be sprayed, but there is no particular limitation on the type and combination in the present invention.

The surface roughness of the substrate after the surface roughening treatment is 3 μm or more, preferably 10 to 30 μm. This is because if the surface roughness is less than 3 μm, the effect of improving the adhesion to “a thin film made of copper or a copper alloy” is not significant. On the other hand, when the surface roughness exceeds 50 μm, the adhesion is good, but the distortion generated in the base material (substrate) is not practical.

Now, in the present invention, after a “thin film made of copper or a copper alloy” is formed on the surface of a substrate, one of the major features of the present invention is “a specific novel chemical treatment in which an oxidizing agent is added. Treatment with a treatment liquid "is performed, and the oxidation treatment of the chemical conversion treatment film generated together with the chemical conversion treatment is performed simultaneously.

In general, "chemical conversion treatment" means that a metal is chemically reacted with a corrosive liquid (chemical conversion liquid) adjusted to a specific condition to form a fixed water-insoluble corrosion product layer on the surface of the metal. The term "treatment" refers to rust prevention, coating base, lubricating base for composition processing, etc., utilizing the physical or chemical properties of the corrosion product.

The “treatment with a specific treatment solution” according to the present invention has almost the same concept as the “chemical conversion treatment”, but in the present invention, particularly, a “thin film made of copper or a copper alloy” formed on a substrate.
Can be said to be unique in that it is treated with a treatment liquid different from that used in the ordinary chemical conversion treatment to form a patina having outstanding characteristics.

As described above, the special treatment liquid used in the present invention includes (a) alkali metal chloride and / or alkaline earth metal chloride to which aluminum powder is added, (b) aluminum chloride, (c) second chloride Oxidation to a solution containing one or more selected from tin, (d) zinc chloride, and (e) lead chloride (the solvent is generally water, but a solvent other than water may be used). To which a so-called "green-blue generating agent" such as alum, copper sulfate or copper nitrate may be added, and the present invention covers all of these. . The oxidizing agent added to the processing solution according to the present invention is not particularly limited, and examples thereof include (a) manganese dioxide (MnO ₂ ), (b) lead dioxide (PbO ₂ ), and (c) Permanganate (KMnO ₄ , NaMnO _{4 etc.} ), (d) chromate and / or dichromate (including chromate and dichromate), (e) iodine compounds containing free iodine ( For example,
It is preferable to use these compounds alone or in combination.

(A) Alkali metal chloride and / or alkaline earth metal chloride with aluminum powder added; (b) aluminum chloride; (c) stannic chloride; (d) zinc chloride; A solution containing one or more kinds selected from lead chloride, or a solution obtained by adding a “green-blue generating agent” such as alum, copper sulfate, or copper nitrate (hereinafter, these solutions are referred to as “the chemical conversion treatment solution of the present invention”). Is tentatively referred to as "a thin film composed of copper or a copper alloy" when it reacts with it to form cuprous chloride (CuCl) or reacts with each other on or in the thin film to form chloride. Produces cuprous copper.

In the present invention, a thin film made of copper or a copper alloy formed on a substrate is treated with a treatment solution obtained by appropriately combining the above-mentioned chemical conversion treatment solution of the present invention and an oxidizing agent, and a chemical conversion treatment reaction and an oxidation reaction are simultaneously performed. It proceeds to form patina.

Hereinafter, the treatment for forming patina with the treatment liquid according to the present invention is performed by setting the processing target object to “a thin film made of copper or a copper alloy formed on a substrate by thermal spraying”, and using the chemical conversion treatment liquid of the present invention as “aqueous aluminum chloride solution”. And the case where the oxidizing agent is manganese dioxide will be described in detail as an example. However, when a thin film made of copper or a copper alloy is formed by means other than thermal spraying,
It has been confirmed that when the chemical conversion treatment liquid of the present invention is other than the aqueous solution of aluminum chloride, even when the oxidizing agent is other than manganese dioxide, substantially the same operation and effect can be obtained under substantially the same conditions.

The concentration of aluminum chloride, which is the chemical conversion treatment solution of the present invention, is not particularly limited, but usually an aqueous solution of 5 to 50% by weight, preferably 20 to 30% by weight is used. Similarly, the amount of the oxidizing agent, manganese dioxide, is not particularly limited, but is usually 3% by weight or more, preferably 5 to 20% by weight. In the treatment, a treatment liquid obtained by adding manganese dioxide to an aqueous solution of aluminum chloride is applied to a “thin film made of copper or a copper alloy” by spraying, or by immersing the thin film in the treatment liquid to form a patina. Is performed.

When this process is performed, it is recognized from a change in the color of the thin film that the "thin film made of copper or copper alloy" is whitened for a moment, and then green and blue are generated over time.

The “mechanism for forming a patina when a thin film made of copper or a copper alloy is treated with the treatment liquid according to the present invention” has not been clearly elucidated at present, but the patina produced by the treatment by X-ray diffraction is chemically. It has been confirmed to be stable basic cupric chloride _{{CuCl 2 · 3Cu (OH)} 2}. Therefore, it is presumed that the following reaction is progressing when it is divided into three processes of (I) chemical reaction, (II) oxidation reaction, and (III) green-blue production reaction.

(I) Chemical reaction (a) Aluminum chloride is partially hydrolyzed.

AlCl ₃ + 3H ₂ O = Al (OH) ₃ + 3HCl (1) (2) The generated hydrochloric acid reacts with copper or a copper alloy or an oxide formed on the surface.

_{2Cu + 2HCl = 2CuCl + H 2} ... (2) Cu 2 O + 2HCl = 2CuCl + H 2 O ... (3) CuO + 2HCl = CuCl 2 + H 2 O ... (4) ( c) the resulting CuCl is causing some disproportionation reaction.

2CuCl = CuCl ₂ + Cu (5) Actually, it is considered that various reactions (for example, the reverse reaction of the equation (4)) occur in addition to the reactions of the above equations (1) to (5).

The reaction represented by the formula (2) does not occur in a normal state, but in the case of a sprayed coating or the like, the coating is rapidly cooled from a high temperature and is a laminate of particles that collided with the base material surface. Residual stress, oxides and pores are present,
It is considered that such a reaction occurs because the electrode potential of the film is lower than that of the same material in a normal state.

On the other hand, alkali metal chlorides (eg, KCl, NaCl, etc.) and / or alkaline earth metal chlorides (eg, MgCl ₂ , CaCl ₂
In the processing solution obtained by adding aluminum powder to ( ₂ ), for example, the following reaction occurs when the aluminum powder is added.

_{6NaCl + 2Al + 6H 2 O =} 2AlCl 3 + 6NaOH + 3H 2 ... (6) Therefore, after the aluminum alone chloride (oxidizing agent are excluded from mind) be considered to have occurred substantially the same reaction as in the processing solution. When such a treatment liquid is used, the chemical conversion treatment liquid of the present invention is prepared by adding aluminum powder to an aqueous solution comprising an alkali metal chloride and / or an alkaline earth metal chloride, that is, after the hydrogen generation is completed. It is preferable to add manganese dioxide in view of the usage efficiency of manganese dioxide.

In this case, a local battery may be formed between aluminum and copper or a lower oxide of copper, and the reaction may be promoted.

In addition, in the case of a processing solution to which a known green-blue generating agent such as alum, copper sulfate, copper nitrate or the like is added, although a part thereof becomes a sulfate or a nitrate, it is considered that the essential reaction is substantially the same. When alum, copper sulfate, copper nitrate, etc. are added in this manner, the effect of slightly changing the color tone of the finally formed green-blue can be obtained. Become slow. Therefore, when adding the above-mentioned known patina-generator, although there is no particular limitation, the amount of addition is preferably adjusted to 1 to 15% by weight, preferably about 1 to 5% by weight.

(II) Oxidation reaction (a) Cuprous chloride is oxidized by manganese dioxide,
It becomes cupric chloride and copper hydroxide.

The _{2CuCl + 2H 2 O + MnO 2} = CuCl 2 + Cu (OH) 2 + Mn (OH) 2 ... (7) 2CuCl + 2H 2 O + MnO 2 = 2Cu (OH) 2 + MnCl 2 ... (8) (b) copper and / or copper oxide manganese dioxide Oxidized or decomposed to copper hydroxide.

_{Cu + 2H 2 O + MnO 2} = 3Cu (OH) 2 + Mn (OH) 2 ... (9) Cu 2 O + 3H 2 O + MnO 2 = 2Cu (OH) 2 + Mn (OH) 2 ... (10) CuO + H 2 O = Cu (OH) 2 ... (11) Note that manganese dioxide (including lead dioxide and permanganate) is not directly involved in the above-mentioned oxidation reaction, but can be Cu, Cu ₂ O, Cu
It is presumed that it acts as a catalyst for the oxidation of Cl and the like, and is a very effective additive for patina formation.

(III) Reaction to produce patina (a) Copper (II) chloride reacts with copper hydroxide to produce basic cupric chloride (patina).

_{CuCl 2 + 3Cu (OH) 2} = CuCl 2 · 3Cu (OH) 2 ... (12) Of course, these reactions (I, II, III) proceeds simultaneously parallel manner rather than alone, and finally chemically It is considered to be a stable compound, patina (basic cupric chloride).

The substrate on which patina was formed by the treatment with the chemical conversion treatment solution of the present invention to which an oxidizing agent was added (that is, the “treatment solution according to the present invention)
Preferably, the curing is combined with drying. In this curing, there is no particular need to heat, and it is usually sufficient to perform the curing at room temperature for 2 to 24 hours.

In this way, it is possible to form a green-blue of uniform color tone with extremely excellent adhesion in a short time.

Next, the present invention will be described more specifically with reference to examples.

<Example> Example 1 First, a pre-degreased copper plate (360 mm width x 360 mm length x 0.3 m
m thickness) was prepared, and the surface of the copper plate was roughened by spray blasting using an alundum powder having a particle size of # 50 to # 250 at an air pressure of 1.5 to 5 kg / cm ² (gauge pressure).

Next, the copper plate was roughened using a copper wire to a thickness of 25 μm.
m of thermal sprayed film (copper) was formed.

The spraying conditions at this time were: spraying method: arc spraying (using a 4RC type machine manufactured by Meteco), spraying distance: 150mm ± 80mm, spraying gun speed: 40m / min, pitch: 20-30mm, working voltage: 35V , Working current: 50 A, Air gap: Fine, Air pressure: 80 psi (5.6 kg / cm ² ), Copper wire: 1.6 mmφ × 2 wires.

Then, the copper sprayed film is coated with "30% by weight of aluminum chloride
A solution obtained by adding 5% by weight of manganese dioxide powder to an aqueous solution of the present invention (that is, the chemical conversion treatment solution of the present invention) is uniformly applied with a brush to form a reaction layer, and then cured at room temperature for 8 hours. Was done.

And, “the patina formed by the present invention described above”,
"Natural patina over 30 years old", "artificial patina commercially available"
And about the state of each patina surface about "artificial patina slate of a commercial item", the state of each patina surface was observed by SEM (scanning electron microscope).

 This SEM observation photograph is shown in FIGS.

As is clear from the comparison of FIGS. 1 to 4, it can be seen that the patina formed by the method of the present invention is very similar in shape and particle size to natural patina.

Further, the patina formed by the method of the present invention has a prominent bluish green color tone, and even when the patina film is rubbed with a fingertip, no peeling occurs at all, which is superior to that of natural patina. It was confirmed that it had a good adhesion.

Further, analysis by X-ray diffraction confirmed that the patina formed by the method of the present invention was basic cupric chloride {CuCl ₂ .3Cu (OH) ₂ }, which is a main component of natural patina.

In addition, when SEM observations were performed on the sections of the “patina formed by the method of the present invention” and the “natural patina”, the cross section of the method of the present invention was roughened as shown in FIG. Almost the entire cross section of the thermal spray coating that penetrated into the surface became patina and was firmly adhered to the base material, and it was clearly recognized that fine pores were present in the thermal spray coating (turquoise). It was found that the structure, appearance, denseness and the like were extremely similar to those of the natural patina shown in FIG.

Example 2 A patina was formed in the same manner as in Example 1 except that an aqueous solution of stannic chloride: 12% by weight was used as the chemical conversion treatment solution of the present invention.

The patina film obtained in this manner was a uniform film having a strong blue color tone and extremely excellent adhesion without any peeling.

Example 3 A patina was formed in the same manner as in Example 1, except that a chemical conversion treatment solution of the present invention was prepared by adding 5% by weight of aluminum powder to a saline solution (NaCl concentration: 5% by weight).

The resulting patina film was uniform, had substantially the same color tone as natural patina, and had extremely excellent adhesion.

Example 4 In this example, alum @ KAl ₃ (SO ₄ ) was added to an aqueous solution containing 30% by weight of aluminum chloride as the chemical conversion treatment solution of the present invention.
_A vermicelli was formed in the same manner as in Example 1 except that 5% by weight of ₂ (OH) ₆ ｝ crystal was used.

The obtained patina film was uniform and had good adhesion without any peeling off.

In addition to these examples, various methods other than the thermal spraying method were used for forming the copper or copper alloy thin film, and the types of the oxidizing agents were variously changed, and tests were performed in which these were variously combined. According to the method of the present invention, it was confirmed that good results could be obtained almost in the same manner as in the example.

<Summary of effects> As described above, according to the present invention, a patina exhibiting the same profound color tone as natural patina and having extremely excellent adhesion can be stably formed on all kinds of substrates in a short time. Since no special equipment or the like can be required, on-site construction is also possible, and application to, for example, repair of patina products is easy. Therefore, it is possible to contribute to the expansion of the concept of creation in a wide range of fields, such as not only roofing materials but also building interior wall materials and decorative articles.

[Brief description of the drawings]

FIG. 1 is a metallographic photograph (magnification: about 8000 times) of the surface of the "green-blue formed by the method of the present invention" by a scanning electron microscope showing the state of the surface. FIG. 2 is a metallographic photograph (magnification: about 80) of a natural patina surface over 30 years old, showing the state of the natural patina surface.
00 times). FIG. 3 is a metallographic photograph (magnification: about 8000) of the surface of the “artificial patina plate of a commercial product” by a scanning electron microscope showing the surface state thereof.
Times). FIG. 4 is a metallographic photograph by a scanning electron microscope (magnification:
About 8000 times). FIG. 5 is a metallographic photograph (magnification: about 300 times) of a scanning electron microscope showing a cross-sectional state of “green and blue formed by the method of the present invention”. FIG. 6 is a metallographic photograph by a scanning electron microscope showing a cross-sectional state of natural patina over 30 years old (magnification: about 36
0 times).

Claims (4)

(57) [Claims] (1) After forming a thin film made of copper or a copper alloy on the surface of a base material on which patina is to be formed, (a) adding aluminum powder to an alkali metal chloride and / or an alkaline earth metal chloride; (B) aluminum chloride, (c) stannic chloride, (d) zinc chloride, (e) a solution containing an oxidizing agent added to a solution containing at least one selected from the group consisting of lead chloride. A method for forming patina, which is characterized by treating. 2. The oxidizing agent to be added is (a) manganese dioxide, (b) lead dioxide, (c) permanganate, (d) chromate and / or dichromate, and (e) free iodine. The method for forming patina according to claim 1, wherein the method is one or two or more selected from iodine compounds containing: 3. A roughening of the surface of a substrate on which patina is to be formed, followed by formation of a thin film made of copper or a copper alloy.
The method for forming patina according to claim 1 or 2. 4. The method for forming a patina according to claim 1, wherein a thin film made of copper or a copper alloy is formed by thermal spraying.